<div id="map"></div>

<script>
    var map = new mapboxgl.Map({
        container: 'map',
        style: 'mapbox://styles/mapbox/dark-v10',
        center: [-87.6298, 41.8781],
        zoom: 17,
        bearing: -12,
        pitch: 60,
        interactive: false
    });

    // pixels the map pans when the up or down arrow is clicked
    var deltaDistance = 100;

    // degrees the map rotates when the left or right arrow is clicked
    var deltaDegrees = 25;

    function easing(t) {
        return t * (2 - t);
    }

    map.on('load', function() {
        map.getCanvas().focus();

        map.getCanvas().addEventListener(
            'keydown',
            function(e) {
                e.preventDefault();
                if (e.which === 38) {
                    // up
                    map.panBy([0, -deltaDistance], {
                        easing: easing
                    });
                } else if (e.which === 40) {
                    // down
                    map.panBy([0, deltaDistance], {
                        easing: easing
                    });
                } else if (e.which === 37) {
                    // left
                    map.easeTo({
                        bearing: map.getBearing() - deltaDegrees,
                        easing: easing
                    });
                } else if (e.which === 39) {
                    // right
                    map.easeTo({
                        bearing: map.getBearing() + deltaDegrees,
                        easing: easing
                    });
                }
            },
            true
        );
    });
</script>
